package br.com.sysmagnus.repository;

import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.Query;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Root;

public abstract class AbstractFacade<T> {
       
        private Class<T> entityClass;
       
        public AbstractFacade(Class<T> entityClass){
                this.entityClass = entityClass;
               
        }
       
        protected abstract EntityManager getEntityManager();
       
        public void create(T entity) {
                getEntityManager().persist(entity);
        }
       
        public void edit(T entity){
                getEntityManager().merge(entity);
        }
       
        public void remove(T entity){
                getEntityManager().remove(getEntityManager().merge(entity));
        }
       
        public T find(Object id){
                return getEntityManager().find(entityClass, id);
        }
       
        public List<T> findAll(){
               
                CriteriaQuery cq =
                                getEntityManager().getCriteriaBuilder().createQuery();
                cq.select(cq.from(entityClass));
                return getEntityManager().createQuery(cq).getResultList();
               
        }
       
        public List<T> findRange(int[] range){
                CriteriaQuery cq =
                                getEntityManager().getCriteriaBuilder().createQuery();
                cq.select(cq.from(entityClass));
                Query q =
                                getEntityManager().createQuery(cq);
                q.setMaxResults(range[1] - range[0]);
                q.setFirstResult(range[0]);
                return q.getResultList();
               
        }
       
        public int count(){
                CriteriaQuery cq =
                                getEntityManager().getCriteriaBuilder().createQuery();
                Root<T> rt = cq.from(entityClass);
                cq.select(getEntityManager().getCriteriaBuilder().count(rt));
                Query q = getEntityManager().createQuery(cq);
                return ((Long) q.getSingleResult()).intValue();
               
        }
       
       
       

}
